"anticlockwise" appears to be [Brit.] and [Aust.], whereas "counterclockwise" is [Amer.] and [Canad.]. Mary(NZ) can probably fill us in on New Zealand usage. What about hyphenated vs non-hyphenated spelling? It seems the non-hyphenated versions dominate?
Jeremy Smith, "Bum Bags and Fanny Packs. A British-American/American-British Dictionary":
anticlockwise adv adj.: counterclockwise
Christopher Davies, "Divided by a Common Language. A Guide to British and American English":
UK | US
anticlockwise | counterclockwise
The Candian Oxford Dictionary:
anticlockwise adv. & adj. Brit. = counter-clockwise
counter-clockwise adv. & adj. N. Amer. adv. in a curve opposite in direction to the movement of the hands of a clock. adj. moving counter-clockwise
The Macquarie Dictionary:
adjective, adverb US → anticlockwise.
adverb 1. in a direction opposite to that of the rotation of the hands of a clock.
--adjective 2. of or relating to movement in this direction.http://www.bartleby.com/61/56/C0685600.html
The American Heritage® Dictionary of the English Language: Fourth Edition.
ADVERB & ADJECTIVE: In a direction opposite to the rotating hands of a clock.